textproduct: Rapid City

KEY MESSAGES

- Warm, breezy, and mostly dry this week supporting elevated to near-critical fire weather conditions at times.

- Daily chances of thunderstorms remain low/isolated through Thursday, before increasing for Friday, Saturday, and Sunday.

DISCUSSION

(This Evening Through Tuesday) Issued at 151 PM MDT Tue May 26 2026

Synoptically-speaking...somewhat of a "stagnant" weather pattern is expected over northeastern Wyoming and western South Dakota over the next several days as longwave ridging over the central CONUS largely controls our weather while longwave troughing with a large/sprawling low pressure system spins to our west over CA/NV. This will support continued warm temperatures, dry and breezy conditions leading to elevated to near-critical fire weather concerns each day, and only a very small chance of a few isolated diurnally-timed showers and thunderstorms each afternoon/evening, especially west in closer proximity to influence from the low. Our potential for daily showers and thunderstorms looks to increase quite a bit Friday, Saturday, and Sunday as the western low weakens and gradually lifts northeast across the Rockies as more of an open shortwave trough, resulting in height falls and better ascent. A smaller-scale surface low will also be located south of our region in the Plains Wednesday and Thursday, but at this time it may be too far south to have much influence on our local convection chances prior to Friday and it then looks to get absorbed by the lifting western low (we'll have to keep an eye on how far north it may drift before then). The lifting western low/trough will become negatively-tilted, perhaps supporting some more robust convection as well as we get into that Friday-Sunday timeframe (an early glance at long-range model soundings do suggest increasing instability/CAPE, but still a lack of shear).

For today, added low-end PoPs across northeast Wyoming where several of the CAMs try to develop a few showers/thunderstorms this afternoon and evening, and slightly reduced winds/wind speeds as NBM guidance is coming in a bit excited, especially given S/SE flow which doesn't usually "overperform" for our area. For now, chances of thunderstorms seem even lower Wednesday compared to today and held with a dry forecast for now, while making a similar downward tweak to winds/gusts. Still, breezy conditions are expected for the next several days, and gusts of 30-40 MPH will be quite common. Overall, thunderstorms are not expected to be severe today or Wednesday, but will pose the usual hazards of lightning, localized small hail, and gusty winds with any stronger cores.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1107 AM MDT Tue May 26 2026

VFR conditions are expected through the forecast period. Isolated showers/storms across NE WY are possible after 19-21z this afternoon; gusty, erratic winds and lightning are the main threats. Gusty southerly winds will continue through the forecast period.

FIRE WEATHER

Issued At 151 PM MDT Tue May 26 2026

Warm, mostly dry, and very breezy conditions are expected across the region this week, resulting in elevated to near-critical fire weather conditions. RH values will be the main weather-driven limiting factor precluding Red Flag conditions, with minimum values generally 16-24 percent each afternoon (driest today). In addition, we're in the middle of green-up...such as it is this year...with varying fuel conditions currently across the forecast area. A very low chance of a few isolated afternoon/evening thunderstorms will also exist just about each day, with the best chances this afternoon focused across northeastern Wyoming with hazards of lightning, small hail, and gusty/erratic winds. Severe thunderstorms are generally not expected over the next several days. Overall RH values may moderate (rise) a bit this weekend as a trough of low pressure supports increased chances of showers and thunderstorms (starting Friday).

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.